Shelter is a basic need, and human ingenuity has arrived at numerous sophisticated methods and materials to meets this need. Among the many methods are those using precast concrete units that are assembled to create a structure. These methods include construction systems incorporating a wide range of precast unit design, from the simple design to the very complex. The most simple precast unit designs are those used in basic, concrete masonry. While concrete masonry units are easy to design, they can result in structures that are considered structurally inferior to those created with larger, reinforced concrete units. Smaller concrete masonry units can crack and chip as well. Working with small masonry units also requires a specialized labor force to implement. As a result, using such a building method can create high labor costs, and it can be difficult to find a qualified crew.
More sophisticated construction systems use concrete columns, beams, and foundation member to create a superstructure. A beam and column joining assembly is set forth in U.S. Pat. No. 4,583,336, issued to Shelangoskie et al. on Apr. 22, 1986. A series of precast foundation elements are also present in the prior art. U.S. Pat. No. 5,103,613 issued to Satoru Kinoshita on Apr. 14, 1992 teaches foundation members interconnected by a binding member having mortises therein for receiving tenons on the bottom of a column. U.S. Pat. No. 4,124,963 issued to Tadayasu Higuchi on Nov. 14, 1978 sets forth a precast unit for providing footing for a building. While the above patents describe a superstructure they provide no teachings on the construction of walls or the like. In addition, the precast units provide little flexibility in increasing structural integrity.
Two U.S. patents present precast units containing wall members. U.S. Pat. No. 4,328,651 issued to Manuel Gutierrez dated May 11, 1982 presents a system having a number of precast units including footing boxes, grade beams, roof beams and a wall panel. The Gutierrez system sets forth an intricate system of interconnecting parts. The intricacies of design limit the flexibility of the system, however. The beams and wall panels would have to be formed to custom lengths and height in order to meet the needs of varying structures. In addition, the wall panels lack flexibility in increasing structural strength. The second patent is U.S. Pat. No. 5,081,805 issued to M. Omar A. Jazzar on Jan. 21, 1992. This patent teaches precast units of half story height that include steel reinforcements. The Jazzar invention requires substantial lifting equipment, however, and is also limited in versatility. Building designs departing from the preformed dimensions require a second, expensive mold, or considerable custom work to arrive at the desired shape.
Authors David A. Sheppard and William R. Phillips illustrate unitary load-bearing or non-load-bearing precast panels in their book Plant-Cast Precast & Prestressed Concrete--A Design Guide, Third Edition, McGraw-Hill Inc., 1989, (see pages 311-13). The same book also illustrates the use of very large, precast, concrete "voided" bearing walls on page 340. The large bearing walls and precast panels, like those in the Gutierrez patent, must be custom formed, requiring large custom molds, a large site slab, and very large lifting equipment. In addition, the immense size of the walls makes them impractical for smaller construction projects.
To the inventors' knowledge, no building system employing preformed members has been developed that provides versatility in design, can accommodate a variety of reinforcement designs, requires relatively small lifting equipment, and that provides for the rapid construction of buildings.